The present invention relates to devices which are responsive to inertia. More particularly, the present invention relates to an omni-directional inertia switching device which may be employed individually as an impact switch or ganged to function as an accelerometer.
Inertia responsive devices are well known and used in a variety of applications. In general, a mass is maintained in a first position until a sufficient force is exerted on the device to move the mass to a second position. Examples of such devices are disclosed in U.S. Pat. Nos. 3,368,044; 3,453,405; 3,818,160; 4,071,723; and 4,594,485. The above list is only exemplary and is not intended to be a complete list of the prior art inertia responsive devices.
U.S. Pat. No. 3,368,044 to Green et al discloses an inertia switch having a ball trapped between two cones. A snap action disk is attached to the vertex of the lower cone. An actuating member extends downwardly from the lower cone and the disk. The snap action disk is circular with a plurality of inwardly extending rounded slots about the periphery thereof. The disk has a central opening with a plurality of outwardly extending rounded slots about the periphery of the opening. The shape of the disk when viewed from a side elevation is generally convex. The switch is actuated when a preselected amount of inertia force causes the ball to overcome the disk and force the lower cone and the actuating member downwardly thereby tripping a toggle switch assembly.
U.S. Pat. No. 3,818,160 to Hitchcock discloses an inertia switch having a ball which rests on a surface at the lower portion of a housing. The housing includes a sidewall which defines an opening in which the ball is disposed. An electrically conductive disk is secured at a ledge of the sidewall at the upper portion of the housing. The disk has a central opening and a plurality of inwardly extending slots about the periphery thereof. The shape of the disk when viewed from a side elevation is generally flat. A leaf spring is in electrical contact with the disk and holds the disk away from a conductive ring. Accordingly, a preselected amount of inertia force will cause the ball to push against the disk overcoming the leaf spring which will come into electrical contact with the ring (i.e., actuate the switch).
U.S. Pat. No. 4,594,485 to Brown, Jr. discloses an impact sensor having a ball enclosed in a housing with a spring. The spring is a hemispherically shaped electrically conductive disk. The ball rests on the disk such that a preselected amount of initial force will cause the ball to push against the disk causing it to flip from a concave or open position to a convex or closed position. In the closed position electrical contact is made between the disk having a terminal and a contact also having a terminal. This sensor may be automatically reset if a pivotable arched contact disposed above a deformable closure member is used.
U.S. Pat. Nos. 3,453,405 and 4,071,723 each disclose a ball supported by a spring in a housing. The U.S. Pat. No. 3,453,405 discloses an inertial switch having a coil spring which extends up into an opening in the ball. The U.S. Pat. No. 4,071,723 discloses a wavy spring washer supporting a cup member which supports the ball.
The prior art devices are complex in that each has many components. Further, due to this complexity these prior art devices are relatively large. Accordingly, a need exists for a smaller, less complex inertia device.